I have no problem admitting my bias in this situation - I have been an Amtrak traveller often in my life and I have always enjoyed my experiences riding America's rails, even the two times I was victim to 12-plus-hour delays.
Recent criticism of the Obama Administration's relatively modest high speed rail proposal suggests that the new rail lines would be subjected to the same kinds of inefficiencies as the Amtrak system. While it is true that high speed rail would require a significant subsidy to build and operate during its first years, there are a lot of reasons why the Amtrak comparison does not hold water.
For one thing, most of the delays which negatively impact Amtrak's popularity will not impact the new high speed rail system. Amtrak trains are frequently delayed by the private railroad corporations on whose rails they run. The new high speed rail system will have its own dedicated tracks and will not be subject to delays by freight trains on the same rails.
Amtrak can't compete with air and vehicle travel in most areas of the country because it simply isn't fast enough. Outside of the northeast corridor most trains are limited to a maximum speed of 79 mph. In more congested areas that speed can drop to 10 mph. These factors often limit Amtrak trains to an average speed over their schedule of around 40 mph. Even the northeast corridor's vaunted Acela service, currently the US's only high speed rail, has a maximum speed of 150 mph with an average speed of 80 mph. At these speeds Acela successfully competes with airline and automobile traffic along the I-95 megalopolis. The proposals being considered for high speed rail involve trains running at an average of 80 mph in the midwest and at speeds of up to 225 mph in California and Florida. This will make these trains competitive and attractive to business and leisure travellers.
Amtrak is also hurt by its scope - by mandate Amtrak provides a nationwide passenger service, from San Diego, to Seattle, to Portland, Maine, and all the way to Miami, Amtrak stretches from corner-to-corner of the United States. This means that it has to serve many smaller communities like Fulton, Kentucky and Alpine, Texas, where ridership is small and time is lost. On the new high speed rail lines, shorter corridors between large cities will be served. Instead of running a single train from Miami to Chicago, as Amtrak might have done during its better days, the new high speed rail network would run a train from Miami to Orlando, or Miami to Jacksonville. Studies have shown that there will be more frequent ridership along these corridors and that they will be cost competitive with the airlines.
Finally, the claim from opponents of high speed rail is that Americans are simply to connected to their automobiles or the jet-set lifestyle that they have known since the Nixon Administration collaborated with private rail companies to kill passenger rail in the United States. The average joe-sixpack will not want to ride the rails. However, the last decade has shown amazing increases in ridership and public support for Amtrak. Furthermore, municipalities from throughout the country, even in some of its most conservative areas, are lobbying for inclusion on Amtrak routes. It makes sense that this same enthusiasm will carry over to newer, faster and better trains.